The explosive power of so-called secondary explosives and certain initiating explosives used in most modern munitions has been developed to a remarkable degree of destructiveness. This is due in part to the use of several components in the explosive. Consequently, not only are the primary detonation products factors generating the destructive force but also the secondary combustible gases and heat of reaction. The former are produced by the metastable nitrogenous and organic compounds present. The latter are produced by metal powders and oxidizers incorporated into the explosive.
Processes for disposing of such secondary explosives in munitions have typically involved non-confined detonation, incineration, or open burning. To obtain the explosive from the munitions, the munitions are often opened by sawing or mechanical cleaving. This process enables reclamation of the metal munition housings or shell. However, aside from being very dangerous, these techniques result in release of large quantities of toxic and/or otherwise undesirable compounds into the air, ground and ground water.
Disposal efforts have also included slicing the munitions open and washing out the explosive with water. This process results in contamination of large quantities of water with the recovered explosive and explosive by products. This water is toxic to aquatic life and cannot be returned to the environment without removal of the explosives. Some effort has been devoted to development of methods to remove these explosives from water. In particular, activated carbon such as carbon black or charcoal will absorb much of the explosive and has been used to treat the water solutions formed by washing the explosive from the opened munitions. Not all of the explosive is removed from the water, however. Moreover, the carbon treatment results in additional processing of the carbon which can retain as much as 0.5 grams of explosive per kilogram of carbon.
Several other processing methods have been proposed for treatment of the explosive waste water. Photolysis by ultraviolet irradiation of the explosive-laden water will cause degradation of the explosive compounds to neutral and stable compounds such as ammonia and carbon dioxide. Typically, the ultraviolet photolysis can be catalyzed with free radical sources such as ozone or hydrogen peroxide to facilely produce unstable intermediates from the explosives.
This development of degradative processes for explosives is exemplified by Andrews et al, U.S. Pat. No. 4,038,116, which discloses a method for degrading aromatic explosive solutions such as nitrotoluenes, nitramines, and other explosives through the application of ultraviolet energy. Andrews notes that the degrading reaction may be catalyzed by the induction of reactive intermediates through the use of free radical initiators such as acetone or hydrogen peroxide. The Andrews process ultimately produces such byproducts as carbon dioxide and ammonia. However, Andrews initiates his process by "solubilizing" the explosives into a water solution and mixing it with the reactive intermediate.
Problems of the Andrews process include the low, almost null solubility, of organic explosives in aqueous solvent (in the magnitude of 10 ppm). Furthermore, the batch mode processing of Andrews means that a portion of the aqueous explosive solution is processed by recirculation until all measurable amounts of the explosive are removed. This is a time consuming and labor intensive exercise. Wholly apart from the technical problems, the negligible solubility of explosive in water breeds significant impractibilities because vast quantities of water would be required for processing. Therefore, any sort of modular water reactor system for on-site treatment of weapons caches could not be developed. Moreover, the rate of destruction of the explosives is limited due to the very small concentrations of the explosive in the aqueous system. As a result, the method of Andrews et al as well as other aqueous based processes for degradation of explosives fail to provide continuous processing of the explosives.
Such aqueous treatment systems for disposal of munitions are dangerous as well. The addition of water to explosives in the context of a system having the potential for oxidation and generation of heat often provides just that element needed to cause spontaneous combustion or explosion of the munition. This element is especially prevalent when metal powder is present as it is in most modern explosives. The metal powder is often encapsulated by a coating agent such as a fatty acid salt. The encapsulation prevents spurious contact of water and the metal powder but also prevents appropriate aqueous treatment and separation. Moreover, when an aqueous disposal system does penetrate to the surface of the metal powder, the result is often a conflagration. The metal powder is highly reactive with the water. In other respects, however, an aqueous system would seem to be the safest. Its non-combustibility in the presence of flame, heat and sparks would minimize the accidental incineration of the explosive.
Therefore, it is an object of the invention to provide a process for degradation of explosive organic compounds or munitions that enables the use of continuous processing of more concentrated forms of explosive. A further object is the development of a safe process that avoids the explosive potential of aqueous systems. Yet another object is the development of an integrated process for removing the explosive from the munition and converting it to non-explosive chemicals.